• Journal of the Korean Data and Information Science Society
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• 제14권3호
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• pp.631-639
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• 2003

Bayes estimates of reliability for the stress-strength system are obtained with respect to LINEX loss function. A reference prior distribution of the reliability is derived and Bayes estimates of the reliability are also obtained. These Bayes estimates are compared with corresponding estimates under squared-error loss function.

• 정신신체의학
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• 제4권1호
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• pp.146-154
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• 1996

스트레스와 면역기능 간의 관계는 중추신경계, 신경내분비계 및 면역계 간의 의사소통 즉 상호작용에 의해 이루어지고 있다. 중추신경계와 면역계가 상호작용하는 주요 경로는 임파조직의 신경계 wiring system과 신경내분비계다. 면역계는 neuropeptide를 생성하고 이것은 면역반응을 조절한다. 정신사회적 인자와 면역기능 간의 중개자로는 뇌하수체에서 방출되는 peptide, hormone 및 자율신경계 물질이 있다. 시상하부는 내분비계, 신경계 및 면역계를 통합하는 역활을 한다. 특히 시상하부의 paraventricular nucleus가 이 일에 중추적인 역할을 담당한다. 한편 내분비계는 면역계에 의해서 휘이드백을 받는다. 뇌하수체가 면역계를 조절하는 주요 경로로는 시상하부-뇌하수체-부신-흉선축, 시상하부-뇌하수체-성선-흉선축, 송과선-시상하부-뇌하수체축 등이 시사되고 있다. 스트레스와 면역계 간에는 양 방향의 경로가 있는 것으로 가정된다. 즉 스트레스가 면역계에 영향을 미칠 뿐만 아니라 면역계가 정신사회적 기능에 영향을 미칠 수 있다. 따라서 스트레스와 면역기능 간의 관계를 규명하기 위해서는 면역계, 내분비계, 자율신경계 및 뇌활동을 동시에 측정, 비교하여 이들을 통합할 필요가 있다.

• 소성∙가공
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• 제31권6호
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• pp.351-364
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• 2022

The yield criterion, or called yield function, plays an important role in the study of plastic working of a sheet because it governs the plastic deformation properties of the sheet during plastic forming process. In this paper, we propose a modified version of previous anisotropic yield function (Trans. Mater. Process., 31(4) 2022, pp. 214-228) based on J2 and J3 stress invariants. The proposed anisotropic yield model has the 6th-order of stress components. The modified version of the anisotropic yield function in this study is as follows. f(J₂⁰,J₃⁰) ≡ (J₂⁰)³ + α(J₃⁰)² + β(J₂⁰)^3/2 × (J₃⁰) = k⁶ The proposed anisotropic yield function well explains the anisotropic plastic behavior of various sheets such as aluminum, high strength steel, magnesium alloy sheets etc. by introducing the parameters α and β, and also exhibits both symmetrical and asymmetrical yield surfaces. The parameters included in the proposed model are determined through an optimization algorithm from uniaxial and biaxial experimental data under proportional loading path. In this study, the validity of the proposed anisotropic yield function was verified by comparing the yield surface shape, normalized uniaxial yield stress value, and Lankford's anisotropic coefficient R-value derived with the experimental results. Application for the proposed anisotropic yield function to AA6016-T4 aluminum and DP980 sheets shows symmetrical yielding behavior and to AZ31B magnesium shows asymmetric yielding behavior, it was shown that the yield locus and yielding behavior of various types of sheet materials can be predicted reasonably by using the proposed anisotropic yield function.

• 기본간호학회지
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• 제17권2호
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• pp.159-168
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• 2010

Purpose: The purpose of this study was to identify the effects of 12 weeks of Tai Chi exercise on physical function, stress and depression in middle aged women with osteoarthritis. Method: The research design was a nonequivalent control group pretest-posttest design. Forty two participants were assigned to either the experimental group (21) or control group (21). Frequency, percentages, mean, standard deviations, $X^2$-test, Wilcoxon rank sum test and repeated measured ANOVA with SPSS 12.0/PC program were used to analyzed the collected data. Results: For physical function the physical fitness of the experimental group improved significantly more than the control group: Leg strength, balance, flexibility and grip strength. Difficulty of performing activity had a tendency of decrease. Stress showed a tendency of as time passed but the decrease was not significant. Depression decreased and the change was significant. Conclusion: The Tai Chi exercise was effective in improving physical function and reducing the stress and depression of middle aged women with osteoarthritis. Therefore the Tai Chi exercise could be used as a nursing intervention for osteoarthritis in middle aged women.

• 대한기계학회논문집
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• 제19권2호
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• pp.463-474
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• 1995

Modified Vainshtok weight function method is developed. The thermal shock stress intensity factors for elliptical surface cracks existed in the thin and thick walled cylinders are determined. The present results are compared with previous solutions and shown to be good agreement with them.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.268-271
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• 1999

Fatigue life Prediction is investigated analytically based on the fatigue modulus concept. Fatigue modulus degradation rate at any fatigue cycle was assumed as a power function of number of fatigue cycles. New stress function describing the relation of initial fatigue modulus and elastic modulus was used to account for material non-linearity at the first cycle. It was assumed that fatigue modulus at failure is proportional to applied stress level. A new fatigue life prediction equation as a function of applied stress is proposed. The prediction was verified experimentally using cross-ply carbon/epoxy laminate (CFRP) tube.

• 대한기계학회논문집A
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• 제23권6호
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• pp.988-1000
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• 1999

An experimental study is presented for the effect of number of terms of a pewee series type stress function on stress analysis around a hole in tensile loaded plate. The hybrid method coupling photoelastsic data inputs and complex variable formulations involving conformal mappings and analytical continuity is used to calculate tangential stress on the boundary of the hole in uniaxially loaded, finite width tensile plate. In order to measure isochromatic data accurately, actual photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. For qualitative comparison, actual fringes are compared with calculated ones. For quantitative comparison, percentage errors and standard deviations with respect to percentage errors are caculated for all measured points by changing the number of terms of stress function. The experimental results indicate that stress concentration factors analyzed by the hybrid method are accurate within three percent compared with ones obtained by theoretical and finite element analysis.

• 대한기계학회논문집A
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• 제25권10호
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• pp.1671-1677
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• 2001

Cracks at mechanical fastener holes usually nucleate as elliptical comer cracks at the faying surface of the mechanical joints and grow as elliptical arc through cracks. The weight function method for elliptical arc through cracks at mechanical fastener holes has been developed and verified in the part I of this study. In part H, applying the weight function method, the effects of the amount of clearance on the mixed-mode stress intensity (actors are investigated and the change of crack shape is predicted from the analysis for various crack shapes. The stress intensity factors leer inclined crack are analyzed and critical angle at which mode I stress intensity factor becomes maximum is determined.

• 대한기계학회논문집A
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• 제22권2호
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• pp.444-450
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• 1998

In the present investigation, it is attempted to derive a yield function and associated flow rules of loose metal powders to predict plastic deformation and density change during compaction. The loose metal powders yield by shear stress as well as hydrostatic stress and the yield strength is much smaller in tension than compression. Therefore, a yield function for the powders is expressed as a shifted ellipse toward the negative direction in the hydrostatic stress axis in the space defined by the two stresses. Each of parameters A, B and .delta. used in the yield function is expressed as a function of relative density and it is determined by uniaxial strain and hydrostatic compressions using Cu powder. Flow rules obtained by imposing the normality rule to the yield function are applied to the analyses of unidirectional, bidirectional and hydrostatic compressions, resulting in an excellent agreement with experiments. The yield function is further examined by checking volume changes in plane stain, uniaxial strain and shear deformations.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.165-170
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• 2000

The weight function method is an efficient technique to calculate the stress intensity factors for various loading conditions in that only the stress analysis of an uncracked model is required. This paper analyzes the mixed-mode stress intensity factors of surface and deepest points for quarter elliptical surface cracks in mechanical joints by weight function method and the coefficients included in weight function are determined by finite element analyses for reference loadings. Results for the different number of terms in weight function are presented.